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如图所示,放在水平地面上的长木板B长为1.2m,质量为2kg,B与地面间的动摩擦因数为μ1=0.2,一质量为3Kg的小铅块A放在B的左端,A、B之间动摩擦因数为μ2=0.4.刚开始A、B均静止,现使A以3m/s的初速度向右运动之后(g=10m/s2),求:

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    Visitors to the grounds of New College at England's Oxford University pass under an iron gate with the advice: Manners make the man. Even after an appropriate update to: Manners make the person, it's thought-provoking(引人深思的)—especially to today's Americans.

    When we think about what makes the person—it's more likely the degree, the job, the salary. Since when do we count manners as a measure of success?

    We do know that these would make life nicer, if more tolerable. However, we forget or overlook our manners. So , it seems, does everyone else—including, unluckily, our children.

    As a university president, one of my great joys is to visit our campuses and see our students, though we're separated by different generations, interests, and, of course dressing, each student tells me something within the first few minutes that we meet: whether he or she has been taught manners. I sense this in different ways: through her words or her gestures, in the way she listens or how he refers to friends and faculty, how she greets and says goodbye, how he responds when an elderly person enters the room.

    In the absence of manners, however, I make some allowances. For instance, the many ethnic(种族的)groups that students represent often have different explanations of what makes up good manners. In other cases, some students may reject what they've learned to break from their parents and be accepted by other students. Whether students are being different or openly opposing, a recent experience I had with them tells me that there's some hope for reviving and good manners.

    Good manners don't just guarantee acceptance. Good manners open doors to deeper connections and more meaningful roles in our society. Good manners are gentle signals that show we care about one another and allow us to relate to another person in a thoughtful way but at a respectable distance.